I have been thinking about the Slave 1 following the Millennium Falcon to Bespin scene (although it's pretty stupid). For the story to 'make sense' as-is, one might assume Boba Fett would have to calculate the trajectory of the Millennium Falcon to determine that they are heading to Bespin. Then based on this information, contact the Empire, fly through hyperspace to arrive there first, hopping that they do in fact head that way.

However, if this was true, the risk of them changing course and heading off somewhere else is too great to chance it. He would have to know 100% with out a doubt that they were going to Bespin to even consider contacting the Empire.

That said, my thought then leads me to think that he either followed them the whole way to Bespin and landed when they did, or he was able to hack into their star charts to see were they were headed, he might even had a sound amplifier (like those dishes and headphones we see police using to hear what people are saying from across the way) and overheard their conversation.

I am not sure if it would work, adding a FX Slave 1 flying off in the background as the Millennium Falcon approached Bespin ('cause we already know he is being followed), or adding and audio track to the cockpit shot of the Slave 1 overhearing Han mention 'Bespin', as far as the story flows, but it might be something to think about. Either that it's one of those ideas that would end up taking away more than adding to the scene.